ExplodedGraph.h revision 7a95de68c093991047ed8d339479ccad51b88663
1//=-- ExplodedGraph.h - Local, Path-Sens. "Exploded Graph" -*- C++ -*-------==// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines the template classes ExplodedNode and ExplodedGraph, 11// which represent a path-sensitive, intra-procedural "exploded graph." 12// See "Precise interprocedural dataflow analysis via graph reachability" 13// by Reps, Horwitz, and Sagiv 14// (http://portal.acm.org/citation.cfm?id=199462) for the definition of an 15// exploded graph. 16// 17//===----------------------------------------------------------------------===// 18 19#ifndef LLVM_CLANG_GR_EXPLODEDGRAPH 20#define LLVM_CLANG_GR_EXPLODEDGRAPH 21 22#include "clang/AST/Decl.h" 23#include "clang/Analysis/AnalysisContext.h" 24#include "clang/Analysis/ProgramPoint.h" 25#include "clang/Analysis/Support/BumpVector.h" 26#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" 27#include "llvm/ADT/DepthFirstIterator.h" 28#include "llvm/ADT/FoldingSet.h" 29#include "llvm/ADT/GraphTraits.h" 30#include "llvm/ADT/OwningPtr.h" 31#include "llvm/ADT/SmallPtrSet.h" 32#include "llvm/ADT/SmallVector.h" 33#include "llvm/Support/Allocator.h" 34#include "llvm/Support/Casting.h" 35#include <vector> 36 37namespace clang { 38 39class CFG; 40 41namespace ento { 42 43class ExplodedGraph; 44 45//===----------------------------------------------------------------------===// 46// ExplodedGraph "implementation" classes. These classes are not typed to 47// contain a specific kind of state. Typed-specialized versions are defined 48// on top of these classes. 49//===----------------------------------------------------------------------===// 50 51// ExplodedNode is not constified all over the engine because we need to add 52// successors to it at any time after creating it. 53 54class ExplodedNode : public llvm::FoldingSetNode { 55 friend class ExplodedGraph; 56 friend class CoreEngine; 57 friend class NodeBuilder; 58 friend class BranchNodeBuilder; 59 friend class IndirectGotoNodeBuilder; 60 friend class SwitchNodeBuilder; 61 friend class EndOfFunctionNodeBuilder; 62 63 /// Efficiently stores a list of ExplodedNodes, or an optional flag. 64 /// 65 /// NodeGroup provides opaque storage for a list of ExplodedNodes, optimizing 66 /// for the case when there is only one node in the group. This is a fairly 67 /// common case in an ExplodedGraph, where most nodes have only one 68 /// predecessor and many have only one successor. It can also be used to 69 /// store a flag rather than a node list, which ExplodedNode uses to mark 70 /// whether a node is a sink. If the flag is set, the group is implicitly 71 /// empty and no nodes may be added. 72 class NodeGroup { 73 // Conceptually a discriminated union. If the low bit is set, the node is 74 // a sink. If the low bit is not set, the pointer refers to the storage 75 // for the nodes in the group. 76 // This is not a PointerIntPair in order to keep the storage type opaque. 77 uintptr_t P; 78 79 public: 80 NodeGroup(bool Flag = false) : P(Flag) { 81 assert(getFlag() == Flag); 82 } 83 84 ExplodedNode * const *begin() const; 85 86 ExplodedNode * const *end() const; 87 88 unsigned size() const; 89 90 bool empty() const { return P == 0 || getFlag() != 0; } 91 92 /// Adds a node to the list. 93 /// 94 /// The group must not have been created with its flag set. 95 void addNode(ExplodedNode *N, ExplodedGraph &G); 96 97 /// Replaces the single node in this group with a new node. 98 /// 99 /// Note that this should only be used when you know the group was not 100 /// created with its flag set, and that the group is empty or contains 101 /// only a single node. 102 void replaceNode(ExplodedNode *node); 103 104 /// Returns whether this group was created with its flag set. 105 bool getFlag() const { 106 return (P & 1); 107 } 108 }; 109 110 /// Location - The program location (within a function body) associated 111 /// with this node. 112 const ProgramPoint Location; 113 114 /// State - The state associated with this node. 115 ProgramStateRef State; 116 117 /// Preds - The predecessors of this node. 118 NodeGroup Preds; 119 120 /// Succs - The successors of this node. 121 NodeGroup Succs; 122 123public: 124 125 explicit ExplodedNode(const ProgramPoint &loc, ProgramStateRef state, 126 bool IsSink) 127 : Location(loc), State(state), Succs(IsSink) { 128 assert(isSink() == IsSink); 129 } 130 131 ~ExplodedNode() {} 132 133 /// getLocation - Returns the edge associated with the given node. 134 ProgramPoint getLocation() const { return Location; } 135 136 const LocationContext *getLocationContext() const { 137 return getLocation().getLocationContext(); 138 } 139 140 const StackFrameContext *getStackFrame() const { 141 return getLocationContext()->getCurrentStackFrame(); 142 } 143 144 const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); } 145 146 CFG &getCFG() const { return *getLocationContext()->getCFG(); } 147 148 ParentMap &getParentMap() const {return getLocationContext()->getParentMap();} 149 150 template <typename T> 151 T &getAnalysis() const { 152 return *getLocationContext()->getAnalysis<T>(); 153 } 154 155 const ProgramStateRef &getState() const { return State; } 156 157 template <typename T> 158 Optional<T> getLocationAs() const LLVM_LVALUE_FUNCTION { 159 return Location.getAs<T>(); 160 } 161 162 static void Profile(llvm::FoldingSetNodeID &ID, 163 const ProgramPoint &Loc, 164 const ProgramStateRef &state, 165 bool IsSink) { 166 ID.Add(Loc); 167 ID.AddPointer(state.getPtr()); 168 ID.AddBoolean(IsSink); 169 } 170 171 void Profile(llvm::FoldingSetNodeID& ID) const { 172 // We avoid copy constructors by not using accessors. 173 Profile(ID, Location, State, isSink()); 174 } 175 176 /// addPredeccessor - Adds a predecessor to the current node, and 177 /// in tandem add this node as a successor of the other node. 178 void addPredecessor(ExplodedNode *V, ExplodedGraph &G); 179 180 unsigned succ_size() const { return Succs.size(); } 181 unsigned pred_size() const { return Preds.size(); } 182 bool succ_empty() const { return Succs.empty(); } 183 bool pred_empty() const { return Preds.empty(); } 184 185 bool isSink() const { return Succs.getFlag(); } 186 187 bool hasSinglePred() const { 188 return (pred_size() == 1); 189 } 190 191 ExplodedNode *getFirstPred() { 192 return pred_empty() ? NULL : *(pred_begin()); 193 } 194 195 const ExplodedNode *getFirstPred() const { 196 return const_cast<ExplodedNode*>(this)->getFirstPred(); 197 } 198 199 // Iterators over successor and predecessor vertices. 200 typedef ExplodedNode* const * succ_iterator; 201 typedef const ExplodedNode* const * const_succ_iterator; 202 typedef ExplodedNode* const * pred_iterator; 203 typedef const ExplodedNode* const * const_pred_iterator; 204 205 pred_iterator pred_begin() { return Preds.begin(); } 206 pred_iterator pred_end() { return Preds.end(); } 207 208 const_pred_iterator pred_begin() const { 209 return const_cast<ExplodedNode*>(this)->pred_begin(); 210 } 211 const_pred_iterator pred_end() const { 212 return const_cast<ExplodedNode*>(this)->pred_end(); 213 } 214 215 succ_iterator succ_begin() { return Succs.begin(); } 216 succ_iterator succ_end() { return Succs.end(); } 217 218 const_succ_iterator succ_begin() const { 219 return const_cast<ExplodedNode*>(this)->succ_begin(); 220 } 221 const_succ_iterator succ_end() const { 222 return const_cast<ExplodedNode*>(this)->succ_end(); 223 } 224 225 // For debugging. 226 227public: 228 229 class Auditor { 230 public: 231 virtual ~Auditor(); 232 virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0; 233 }; 234 235 static void SetAuditor(Auditor* A); 236 237private: 238 void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); } 239 void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); } 240}; 241 242// FIXME: Is this class necessary? 243class InterExplodedGraphMap { 244 virtual void anchor(); 245 llvm::DenseMap<const ExplodedNode*, ExplodedNode*> M; 246 friend class ExplodedGraph; 247 248public: 249 ExplodedNode *getMappedNode(const ExplodedNode *N) const; 250 251 InterExplodedGraphMap() {} 252 virtual ~InterExplodedGraphMap() {} 253}; 254 255class ExplodedGraph { 256protected: 257 friend class CoreEngine; 258 259 // Type definitions. 260 typedef std::vector<ExplodedNode *> NodeVector; 261 262 /// The roots of the simulation graph. Usually there will be only 263 /// one, but clients are free to establish multiple subgraphs within a single 264 /// SimulGraph. Moreover, these subgraphs can often merge when paths from 265 /// different roots reach the same state at the same program location. 266 NodeVector Roots; 267 268 /// The nodes in the simulation graph which have been 269 /// specially marked as the endpoint of an abstract simulation path. 270 NodeVector EndNodes; 271 272 /// Nodes - The nodes in the graph. 273 llvm::FoldingSet<ExplodedNode> Nodes; 274 275 /// BVC - Allocator and context for allocating nodes and their predecessor 276 /// and successor groups. 277 BumpVectorContext BVC; 278 279 /// NumNodes - The number of nodes in the graph. 280 unsigned NumNodes; 281 282 /// A list of recently allocated nodes that can potentially be recycled. 283 NodeVector ChangedNodes; 284 285 /// A list of nodes that can be reused. 286 NodeVector FreeNodes; 287 288 /// Determines how often nodes are reclaimed. 289 /// 290 /// If this is 0, nodes will never be reclaimed. 291 unsigned ReclaimNodeInterval; 292 293 /// Counter to determine when to reclaim nodes. 294 unsigned ReclaimCounter; 295 296public: 297 298 /// \brief Retrieve the node associated with a (Location,State) pair, 299 /// where the 'Location' is a ProgramPoint in the CFG. If no node for 300 /// this pair exists, it is created. IsNew is set to true if 301 /// the node was freshly created. 302 ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State, 303 bool IsSink = false, 304 bool* IsNew = 0); 305 306 ExplodedGraph* MakeEmptyGraph() const { 307 return new ExplodedGraph(); 308 } 309 310 /// addRoot - Add an untyped node to the set of roots. 311 ExplodedNode *addRoot(ExplodedNode *V) { 312 Roots.push_back(V); 313 return V; 314 } 315 316 /// addEndOfPath - Add an untyped node to the set of EOP nodes. 317 ExplodedNode *addEndOfPath(ExplodedNode *V) { 318 EndNodes.push_back(V); 319 return V; 320 } 321 322 ExplodedGraph(); 323 324 ~ExplodedGraph(); 325 326 unsigned num_roots() const { return Roots.size(); } 327 unsigned num_eops() const { return EndNodes.size(); } 328 329 bool empty() const { return NumNodes == 0; } 330 unsigned size() const { return NumNodes; } 331 332 // Iterators. 333 typedef ExplodedNode NodeTy; 334 typedef llvm::FoldingSet<ExplodedNode> AllNodesTy; 335 typedef NodeVector::iterator roots_iterator; 336 typedef NodeVector::const_iterator const_roots_iterator; 337 typedef NodeVector::iterator eop_iterator; 338 typedef NodeVector::const_iterator const_eop_iterator; 339 typedef AllNodesTy::iterator node_iterator; 340 typedef AllNodesTy::const_iterator const_node_iterator; 341 342 node_iterator nodes_begin() { return Nodes.begin(); } 343 344 node_iterator nodes_end() { return Nodes.end(); } 345 346 const_node_iterator nodes_begin() const { return Nodes.begin(); } 347 348 const_node_iterator nodes_end() const { return Nodes.end(); } 349 350 roots_iterator roots_begin() { return Roots.begin(); } 351 352 roots_iterator roots_end() { return Roots.end(); } 353 354 const_roots_iterator roots_begin() const { return Roots.begin(); } 355 356 const_roots_iterator roots_end() const { return Roots.end(); } 357 358 eop_iterator eop_begin() { return EndNodes.begin(); } 359 360 eop_iterator eop_end() { return EndNodes.end(); } 361 362 const_eop_iterator eop_begin() const { return EndNodes.begin(); } 363 364 const_eop_iterator eop_end() const { return EndNodes.end(); } 365 366 llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); } 367 BumpVectorContext &getNodeAllocator() { return BVC; } 368 369 typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap; 370 371 std::pair<ExplodedGraph*, InterExplodedGraphMap*> 372 Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd, 373 llvm::DenseMap<const void*, const void*> *InverseMap = 0) const; 374 375 ExplodedGraph* TrimInternal(const ExplodedNode* const * NBeg, 376 const ExplodedNode* const * NEnd, 377 InterExplodedGraphMap *M, 378 llvm::DenseMap<const void*, const void*> *InverseMap) const; 379 380 /// Enable tracking of recently allocated nodes for potential reclamation 381 /// when calling reclaimRecentlyAllocatedNodes(). 382 void enableNodeReclamation(unsigned Interval) { 383 ReclaimCounter = ReclaimNodeInterval = Interval; 384 } 385 386 /// Reclaim "uninteresting" nodes created since the last time this method 387 /// was called. 388 void reclaimRecentlyAllocatedNodes(); 389 390private: 391 bool shouldCollect(const ExplodedNode *node); 392 void collectNode(ExplodedNode *node); 393}; 394 395class ExplodedNodeSet { 396 typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy; 397 ImplTy Impl; 398 399public: 400 ExplodedNodeSet(ExplodedNode *N) { 401 assert (N && !static_cast<ExplodedNode*>(N)->isSink()); 402 Impl.insert(N); 403 } 404 405 ExplodedNodeSet() {} 406 407 inline void Add(ExplodedNode *N) { 408 if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N); 409 } 410 411 typedef ImplTy::iterator iterator; 412 typedef ImplTy::const_iterator const_iterator; 413 414 unsigned size() const { return Impl.size(); } 415 bool empty() const { return Impl.empty(); } 416 bool erase(ExplodedNode *N) { return Impl.erase(N); } 417 418 void clear() { Impl.clear(); } 419 void insert(const ExplodedNodeSet &S) { 420 assert(&S != this); 421 if (empty()) 422 Impl = S.Impl; 423 else 424 Impl.insert(S.begin(), S.end()); 425 } 426 427 inline iterator begin() { return Impl.begin(); } 428 inline iterator end() { return Impl.end(); } 429 430 inline const_iterator begin() const { return Impl.begin(); } 431 inline const_iterator end() const { return Impl.end(); } 432}; 433 434} // end GR namespace 435 436} // end clang namespace 437 438// GraphTraits 439 440namespace llvm { 441 template<> struct GraphTraits<clang::ento::ExplodedNode*> { 442 typedef clang::ento::ExplodedNode NodeType; 443 typedef NodeType::succ_iterator ChildIteratorType; 444 typedef llvm::df_iterator<NodeType*> nodes_iterator; 445 446 static inline NodeType* getEntryNode(NodeType* N) { 447 return N; 448 } 449 450 static inline ChildIteratorType child_begin(NodeType* N) { 451 return N->succ_begin(); 452 } 453 454 static inline ChildIteratorType child_end(NodeType* N) { 455 return N->succ_end(); 456 } 457 458 static inline nodes_iterator nodes_begin(NodeType* N) { 459 return df_begin(N); 460 } 461 462 static inline nodes_iterator nodes_end(NodeType* N) { 463 return df_end(N); 464 } 465 }; 466 467 template<> struct GraphTraits<const clang::ento::ExplodedNode*> { 468 typedef const clang::ento::ExplodedNode NodeType; 469 typedef NodeType::const_succ_iterator ChildIteratorType; 470 typedef llvm::df_iterator<NodeType*> nodes_iterator; 471 472 static inline NodeType* getEntryNode(NodeType* N) { 473 return N; 474 } 475 476 static inline ChildIteratorType child_begin(NodeType* N) { 477 return N->succ_begin(); 478 } 479 480 static inline ChildIteratorType child_end(NodeType* N) { 481 return N->succ_end(); 482 } 483 484 static inline nodes_iterator nodes_begin(NodeType* N) { 485 return df_begin(N); 486 } 487 488 static inline nodes_iterator nodes_end(NodeType* N) { 489 return df_end(N); 490 } 491 }; 492 493} // end llvm namespace 494 495#endif 496